“We are spending $80 billion locking people up. Think about what it would mean if we invested that money in our people instead of more jails,” Sanders wrote in a tweet, attaching a link for people to see his discussion with Booker on the issue on Facebook.

In early February, he lambasted U.S. Attorney General Sessions over his clampdown on marijuana. In 2015, Sanders also introduced a legislation to end federal ban on marijuana.

Sanders backing Booker is a natural extension of his stance on cannabis.

Observers, meanwhile, say the 76-year-old Sanders could possibly run for president again for 2020. Legalizing marijuana is expected to be a hot topic in the upcoming presidential campaigns as more states move towards legalization.